1. Field of the Invention
The present invention relates to a three-dimensional (3D) display device, and in particular, to an autostereoscopy-type 3D display device.
2. Description of Related Art
Generally, 3D displays supply different views to the left and right eyes of a user such that the user can have the depth perception of the viewing images. The 3D displays may be classified into a stereoscopic display where the user should wear viewing aids, such as polarizing glasses, and an autostereoscopic display where the user can see the desired 3D image without wearing such viewing aids.
A common autostereoscopic display utilizes an optical separation element (or optical isolation element), such as a lenticular lens, a parallax barrier or a microlens array, to spatially separate or isolate the left-eye image part and the right-eye image part displayed at the image display unit in the directions of the left and right eyes of the user, respectively. For example, the parallax barrier may be formed with a liquid crystal shutter utilizing a transmission type liquid crystal display, and in this case, it may be converted between a 2D mode and a 3D mode.
FIG. 13 is a schematic view of a 3D display device using a parallax barrier according to prior art, and FIG. 14 is a partial sectional view of the 3D display device of FIG. 13.
As shown in the drawings, the 3D display device includes an image display unit 3 where sub-pixels 1L corresponding to the left-eye image part and sub-pixels 1R corresponding to the right-eye image part are arranged in a pattern, and a parallax barrier 9 placed in front of the image display unit 3 with slit-shaped light interception and light transmission portions 5 and 7 longitudinally arranged in the direction of the column of the array of sub-pixels 1 (i.e., in the direction of the Y axis of FIG. 13).
Sets of red (r), green (g) and blue (b) sub-pixels 1 are repeatedly arranged in the direction of the row of the array (i.e., in the direction of the axis X of FIG. 13), and the same-colored sub-pixels are serially arranged in the direction of the column of the array. The parallax barrier 9 has light interception and light transmission portions 5 and 7 alternately and repeatedly arranged in the direction of the row of the array.
With the above structure, the right-eye image part displayed at the right-eye sub-pixels 1R of the image display unit 3 is separated to the right eye of the viewer through the light transmission portions 7 of the parallax barrier 9, and the left-eye image part displayed at the left-eye sub-pixels 1L of the image display unit 3 is separated to the left eye of the viewer through the light transmission portions 7 of the parallax barrier 9. Consequently, the viewer perceives the images of the image display unit 3 as 3D images.
As described above, the prior art-based parallax barrier 9 has slit-shaped light transmission portions 7 longitudinally extending in the direction of the column of the array to display the images of the display unit 3 as 3D images. With such a structure, the horizontal resolution of the 3D images (i.e., measured in the direction of the row of the array, and referred to hereinafter as the horizontal resolution) is at best half the horizontal resolution of the 2D images.
That is, with the 3D display device shown in FIG. 13, among the six sub-pixels 1 continuously arranged in the direction of the row of the array, the three odd-numbered sub-pixels 1R corresponding to the right-eye image part form one pixel R1′ for the right-eye image, and the remaining three even-numbered sub-pixels 1L corresponding to the left-eye image part form one pixel L1′ for the left-eye image. Further, among the next group of six sub-pixels 1 continuously arranged in the direction of the row of the array, the three odd-numbered sub-pixels 1R corresponding to the right-eye image part form one pixel R2′ for the right-eye image, and the remaining three even-numbered sub-pixels 1L corresponding to the left-eye image part form one pixel L2′ for the left-eye image.
Consequently, the horizontal resolution of the left-eye image and the right-eye image is lowered to be half the horizontal resolution of the 2D image where one pixel P1 or P2, as shown in FIG. 15, is formed with three sub-pixels 11 continuously arranged in the direction of the row of the array (in the direction of the X axis of FIG. 15). Because of such reduction in resolution, it is difficult to realize high resolution 3D images with the prior art-based 3D display device.
Meanwhile, with the recently developed 3D display devices, as the pixel size is gradually reduced, the sub-pixels arranged in the direction of the row of the array are grouped together by two or three, and the right-eye image signals and the left-eye image signals are alternately and repeatedly input thereto.
FIGS. 16 and 17 are schematic views of an image display unit and a parallax barrier of 3D display devices according to other prior art, respectively.
FIG. 16 illustrates the way of alternately and repeatedly inputting the right-eye image signals R and the left-eye image signals L at an image display unit 1′ to a plurality of sub-pixel pairs 1′ arranged in the direction of the row of the array of sub-pixels 1′ (in the direction of the X axis of FIG. 16). In this case, the light transmission portions 7′ of a parallax barrier 13 are separated by light interception portions 5′, and are disposed between a pair of sub-pixels 1R′ corresponding to the right-eye image part and a pair of sub-pixels 1L′ corresponding to the left-eye image part.
FIG. 17 illustrates the way of alternately and repeatedly inputting the right-eye image signals R and the left-eye image signals L at an image display unit 15 to a plurality of sub-pixels 1″ grouped by three and arranged in the direction of the row of the array of sub-pixels 1″ (in the direction of the X axis of FIG. 17). In this case, the light transmission portions 7″ of a parallax barrier 17 are separated by light interception portions 5″, and are disposed between three sub-pixels 1R″ corresponding to the right-eye image part and three sub-pixels 1L″ corresponding to the left-eye image part.
With the 3D display devices shown in FIGS. 16 and 17, the horizontal resolution of the left-eye image and the right-eye image is also lowered to be half the horizontal resolution of the 2D image shown in FIG. 15.